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                           IBM ECA
              Engineering Change Announcement

Parts removed from this machine and returned to IBM must be genuine,
                      unaltered IBM Parts

         IBM World Trade Corporation, CE Department Germany
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 EC NUMBER         :  ECC80656     DATE             : 93-06-17
 MANDATORY         :  N
 AUTOMATIC SHIPMENT:  N            SERVICE CODE     : 33
 PARTS SOURCE      :  YASU         AVAILABILITY DATE: 92/05
                                                                                
 PURPOSE:                                                                       

 To prevent memory error problems which occur when Bus Master                   
 Adapter is installed in the PS/55 Model 5551-T Stage 2.                        
  (Stage 2 machine has a white power switch lever)                              
                                                                                
 The following adapters have Bus Master Function.                               
 -Micro Channel SCSI Adapter/A (16Bit,32Bit)                                    
 -Inteligent Communication Adapter/A Portmaster                                 
 -Numeric Processing Adapter                                                    
 -Japanese Voice Adapter/A                                                      
                                                                                

 Type             Machines Affected                             
 Mod.  With       and/or Feature/Device    B/M to be  Serv Syst 
 Stg.  B/M        Description              Installed  Hour Hour 

 Plant 98                                                       

 5551- B/M0005551 S/N RANGE                B/M79F5494 00.5 00.5 
   T09 B/M0005551    970000K --> 978503K   B/M79F5494 00.5 00.5 
   T0A B/M0005551    970000N --> 970571P   B/M79F5494 00.5 00.5 
   T0B B/M0005551    970000S --> 971348S   B/M79F5494 00.5 00.5 
   T19 B/M0005551    97FA001 --> 97FG132   B/M79F5494 00.5 00.5 
   T1A B/M0005551    97HA001 --> 97HF956   B/M79F5494 00.5 00.5 
   T1B               97LA001 --> 97LB875                        

                                                                                
 PHYSICAL CHECK:                                                                

 If Bus Master Adapter is installed in the 5551-T Stage 2, only                 
 when all of the following conditions are satisfied, you must                   
 apply this FBM.                                                                
                                                                                
  1)EC number of the System Board P/N 23F3346 ---> EC# C12856x                  
                                             (x is any alphabet)                
  2)System Board Memory Size ---> 8MB MAX                                       
                              (exclude 2-8MB Expansion Memory)                  
                                                                                
 PREREQUISITES: NONE                                                            
                                                                                
 COMPANION: NONE                                                                
                                                                                
 CONCURRENT: NONE                                                               
                                                                                
 DETAIL:                                                                        

 Replace the System Board in the system unit.                                   
                                                                                
 NOTES:                                                                         

 Return the removed part with EC completion report to stock                     
 center as soon as possible after installing this FBM.                          
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